ConstProp: Remove const when rvalue check fails.

rust-lang · Nov 28, 2023 · a95ffcf · a95ffcf
1 parent aef5074
commit a95ffcf
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Showing 2 changed files with 7 additions and 3 deletions.
diff --git a/compiler/rustc_mir_transform/src/const_prop.rs b/compiler/rustc_mir_transform/src/const_prop.rs
@@ -445,6 +445,7 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
 
         // FIXME we need to revisit this for #67176
         if rvalue.has_param() {
+            trace!("skipping, has param");
             return None;
         }
         if !rvalue
@@ -724,7 +725,11 @@ impl<'tcx> Visitor<'tcx> for ConstPropagator<'_, 'tcx> {
     fn visit_assign(&mut self, place: &Place<'tcx>, rvalue: &Rvalue<'tcx>, location: Location) {
         self.super_assign(place, rvalue, location);
 
-        let Some(()) = self.check_rvalue(rvalue) else { return };
+        let Some(()) = self.check_rvalue(rvalue) else {
+            trace!("rvalue check failed, removing const");
+            Self::remove_const(&mut self.ecx, place.local);
+            return;
+        };
 
         match self.ecx.machine.can_const_prop[place.local] {
             // Do nothing if the place is indirect.

diff --git a/tests/mir-opt/const_prop/issue_118328.size_of.ConstProp.diff b/tests/mir-opt/const_prop/issue_118328.size_of.ConstProp.diff
@@ -12,8 +12,7 @@
           StorageLive(_1);
           _1 = const 0_usize;
           _1 = const _;
--         _0 = _1;
-+         _0 = const 0_usize;
+          _0 = _1;
           StorageDead(_1);
           return;
       }